package com.example.mq.mqserver.datacenter;

import com.example.mq.common.MqException;
import com.example.mq.mqserver.core.Binding;
import com.example.mq.mqserver.core.Exchange;
import com.example.mq.mqserver.core.MSGQueue;
import com.example.mq.mqserver.core.Message;

import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.Exchanger;

/**
 * @Description: 管理内存中的所有数据
 * 这个类提供的一些方法，可能会在多线程环境下被使用，因此要注意线程安全问题
 * @Author: liudong
 * @Time: 2024/5/14
 */

public class MemoryDataCenter {
    //key是exchangeName，value是Exchange对象
    private ConcurrentHashMap<String, Exchange> exchangeMap = new ConcurrentHashMap<>();
    //key是queueName，value是MSGQueue对象
    private ConcurrentHashMap<String, MSGQueue> queueMap = new ConcurrentHashMap<>();
    //第一个key是exchangeName，第二个key是queueName
    private ConcurrentHashMap<String, ConcurrentHashMap<String, Binding>> bindingsMap = new ConcurrentHashMap<>();
    //key是messageId，value是Message对象
    private ConcurrentHashMap<String, Message> messageMap = new ConcurrentHashMap<>();
    //key是queueName，valu是一个Message的链表
    //发送消息
    private ConcurrentHashMap<String, LinkedList<Message>> queueMessageMap = new ConcurrentHashMap<>();
    //第一个key是queueName 第二个key是messageId
    //未确认消息
    private ConcurrentHashMap<String, ConcurrentHashMap<String, Message>> queueMessageWaitAckMap = new ConcurrentHashMap<>();

    public void insertExchange(Exchange exchange) {
        exchangeMap.put(exchange.getName(), exchange);
        System.out.println("[MemoryDataCenter] 新交换机添加成功！ exchangeName = " + exchange.getName());
    }

    public void deleteExchange(String exchangeName) {
        exchangeMap.remove(exchangeName);
        System.out.println("[MemoryDataCenter] 交换机删除成功！ exchangeName = " + exchangeName);

    }

    public Exchange getExchange(String exchangeName) {
        return exchangeMap.get(exchangeName);
    }

    public void insertQueue(MSGQueue queue) {
        queueMap.put(queue.getName(), queue);
        System.out.println("[MemoryDataCenter] 新队列添加成功！ queueName = " + queue.getName());

    }

    public void deleteQueue(String queueName) {
        queueMap.remove(queueName);
        System.out.println("[MemoryDataCenter] 队列删除成功！ queueName = " + queueName);

    }

    public MSGQueue getQueue(String queueName) {
        return queueMap.get(queueName);
    }

    public void insertBinding(Binding binding) throws MqException {
        //先使用exchangeName查一下hash表是否存在，不存在就创建一个
//        ConcurrentHashMap<String,Binding> bindingMap = bindingsMap.get(binding.getExchangeName());
//        if (bindingMap == null){
//            bindingMap = new ConcurrentHashMap<>();
//            bindingsMap.put(binding.getExchangeName(),bindingMap);
//        }
        //先使用exchangeName查一下hash表是否存在，不存在就创建一个
        ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.computeIfAbsent(binding.getExchangeName(), k -> new ConcurrentHashMap<>());

        synchronized (bindingMap) {
            //再根据queueName查一下，如果已经存在，就抛出异常，不存在才能插入
            if (bindingMap.get(binding.getQueueName()) != null) {
                throw new MqException("[MemoryDataCenter] 绑定已经存在！ exchangeName = " + binding.getExchangeName() + ",queueName=" + binding.getQueueName());
            }
            bindingMap.put(binding.getQueueName(), binding);
        }
        System.out.println("[MemoryDataCenter] 新绑定添加成功！ exchangeName = " + binding.getExchangeName() + "queueName = " + binding.getQueueName());

    }

    //获取绑定有两种方法
    //1.根据exchangeName和queueName确定唯一一个Binding
    public Binding getBinding(String exchangeName, String queueName) {
        ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.get(exchangeName);
        if (bindingMap == null) {
            return null;
        }
        return bindingMap.get(queueName);
    }

    //2.根据exchangeName获取到所有的Binding
    public ConcurrentHashMap<String, Binding> getBindings(String exchangeName) {
        return bindingsMap.get(exchangeName);
    }

    public void deleteBinding(Binding binding) throws MqException {
        ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.get(binding.getExchangeName());
        if (bindingMap == null) {
            //该交换机没有绑定任何队列，报错
            throw new MqException("[MemoryDataCenter] 绑定不存在！ exchangeName = " + binding.getExchangeName() + ",queueName" + binding.getQueueName());
        }
        bindingMap.remove(binding.getQueueName());
        System.out.println("[MemoryDataCenter] 绑定删除成功！ exchangeName = " + binding.getExchangeName() + "queueName = " + binding.getQueueName());

    }

    //添加消息
    public void addMessage(Message message) {
        messageMap.put(message.getMessageId(), message);
        System.out.println("[MemoryDataCenter] 新消息添加成功！ messageId = " + message.getMessageId());
    }

    //根据id查询消息
    public Message getMessage(String messageId) {
        return messageMap.get(messageId);
    }

    //根据id删除消息
    public void removeMessage(String messageId) {
        messageMap.remove(messageId);
        System.out.println("[MemoryDataCenter] 消息被移除！ messageId = " + messageId);
    }

    //发送消息到指定队列
    public void sendMessage(MSGQueue queue, Message message) {
        //把消息放到对应的队列数据结构中
        //先根据队列的名字，找到队列对应的消息链表
//        LinkedList<Message> messages = queueMessageMap.get(queue.getName());
//        if (messages == null){
//            messages = new LinkedList<>();
//            queueMessageMap.put(queue.getName(),messages);
//        }
        LinkedList<Message> messages = queueMessageMap.computeIfAbsent(queue.getName(), k -> new LinkedList<>());
        //再把消息加载到messages里面
        synchronized (messages) {
            messages.add(message);
        }
        //把该消息往消息中心插一下，加入message已经在消息中心存在，重复插入也没关系
        //主要是根据messageId，对应的message内容是一样的
        addMessage(message);
        System.out.println("[MemoryDataCenter] 消息被投递到队列中！ messageId = " + message.getMessageId());
    }

    //从队列中取消息
    public Message pollMessage(String queueName) {
        //根据队列名查找对应的队列的消息列表
        LinkedList<Message> messages = queueMessageMap.get(queueName);
        //如果没找到说明队列中没有任何消息
        if (messages == null) {
            return null;
        }
        synchronized (messages) {
            //如果大小为0，也说明队列中没有任何消息
            if (messages.size() == 0) {
                return null;
            }
            //链表中有头元素就进行头删
            Message currentMessage = messages.remove(0);
            System.out.println("[MemoryDataCenter] 消息从队列中取出 messageId = " + currentMessage.getMessageId());
            return currentMessage;
        }
    }

    //获取队列中指定的消息
    public int getMessageCount(String queueName) {
        LinkedList<Message> messages = queueMessageMap.get(queueName);
        if (messages == null) {
            //队列中没有消息
            return 0;
        }
        synchronized (messages) {
            return messages.size();
        }
    }

    //添加未确认消息
    public void addMessageWaitAck(String queueName, Message message) {
        ConcurrentHashMap<String, Message> messageHashMap = queueMessageWaitAckMap.computeIfAbsent(queueName, k -> new ConcurrentHashMap<>());
        //插入数据
        messageHashMap.put(message.getMessageId(), message);
        System.out.println("[MemoryDataCenter] 消息进入待确认队列！ messageId = " + message.getMessageId());
    }

    //删除未确认消息（消息已经确认了）
    public void removeWaitMessageAck(String queueName, String messageId) {
        ConcurrentHashMap<String, Message> messageHashMap = queueMessageWaitAckMap.get(queueName);
        if (messageHashMap == null) {
            return;
        }
        messageHashMap.remove(messageId);
        System.out.println("[MemoryDataCenter] 消息从待确认队列删除！ messageId = " + messageId);
    }

    //获取指定的未确认消息
    public Message getWaitMessageAck(String queueName, String messageId) {
        ConcurrentHashMap<String, Message> messageHashMap = queueMessageWaitAckMap.get(queueName);
        if (messageHashMap == null) {
            return null;
        }
        return messageHashMap.get(messageId);
    }

    //从硬盘上读取数据，把硬盘上之前持久化存储的各个维度的数据恢复到内存中
    public void recovery(DiskDataCenter diskDataCenter) throws IOException, MqException, ClassNotFoundException {
        //清空之前的所有数据
        exchangeMap.clear();
        queueMap.clear();
        bindingsMap.clear();
        messageMap.clear();
        queueMessageMap.clear();

        //1.恢复所有交换机数据
        List<Exchange> exchanges = diskDataCenter.selectAllExchanges();
        for (Exchange exchange : exchanges) {
            exchangeMap.put(exchange.getName(), exchange);
        }

        //2.恢复所有队列数据
        List<MSGQueue> queues = diskDataCenter.selectAllQueues();
        for (MSGQueue queue : queues) {
            queueMap.put(queue.getName(), queue);
        }
        //3.恢复所有绑定数据
        List<Binding> bindings = diskDataCenter.selectAllBindings();
        for (Binding binding : bindings) {
            ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.computeIfAbsent(binding.getExchangeName(), k -> new ConcurrentHashMap<>());
            bindingMap.put(binding.getQueueName(), binding);
        }
        //4，恢复所有消息数据
        //遍历所有的队列，根据每个队列的名字获取所有的消息
        for (MSGQueue queue : queues) {
            LinkedList<Message> messages = diskDataCenter.loadAllMessageFromQueue(queue.getName());
            queueMessageMap.put(queue.getName(), messages);
            for (Message message : messages) {
                messageMap.put(message.getMessageId(), message);
            }
        }
    }


}





